Our steps are grooved plastic steps that came with the tub and the ice sweeps right off.
We bought some slip on flip flops for us and for guests at a sporting good store for $5.88 that have a more sticky rubber sole. When we looked at slip on's I ran my hand on the sole, if it slipped easily, it was not good for our use, if it slip very slowly on my hand or not at all, it was good to buy. I also bought a pair of tie boots at Walmart that I slip on for use in cleaning off the spa or getting it ready to use.
We tried a runner rug in the past, putting it out each time we used the tub, but it was more bother than it was worth. We still use the runner for company though and put it by the fireplace to dry after we roll it up.